If you have a truck, you’ve probably thought about off-road wheels and tires at some point. How big should the tire be? How much wheel do you need? What are the benefits of having a wide tire vs a skinny one? How much do they cost?
The purpose of this article is to get a bird’s eye view of wheels and tires. I’ll get into specifics, including airing down, costs, brands, and other details in later posts. As usual, I’ll be focused primarily on the F-250, but the concepts here will help you no matter what you drive.
What Kind of Driving Do You Do?
The first thing you really need to understand is how you use, or plan on using, your truck. Keep in mind there can be a big difference between what you think you do and what you actually do. For most people, the majority of driving happens on pavement. The time we spend getting from home to the dirt, or commuting from home to work, significantly outlasts the time actually spent in the back country.
That being said, what’s your focus? Are you a casual weekender that just wants to get away from the city for an afternoon, or even a weekend? Do you expect to spend several days at a time, or a week or more in the middle of nowhere? Are you looking at rock-crawling and doing circles in mud puddles and you’re not concerned with handling and mileage and wear?
Do you spend any time on the beach? Or in the desert? Are you going to be in the forest? Is there a lot of rain where you roll? Rocky terrain?
If you are a casual weekender, just looking for a campground or spot a little out of the way, you probably don’t need to upgrade from your stock setup. Modern 4×4 trucks have a lot of features such as anti lock brakes, traction control, multiple 4×4 settings, good ground clearance and manual gearing features that will get you up any gravel road, and many other roads less traveled. Just take it slow, and if the road looks like it could get you into trouble, backtrack and pick another route. You’ll still be able to see much of the country that you otherwise would never know exists.
If, on the other hand, you want to spend days at a time hiding from civilization, if you want more capability, or if you just want some extra insurance when the road turns unexpectedly rough, consider an upgrade.
Something else to think about: I read somewhere that you should just roll on stock wheels and tires until you find yourself in a situation where you say “I really needed to have more clearance” or “I could seriously have used a wider tire”. I disagree with this philosophy. Why get yourself stuck when you can plan ahead and keep from getting into trouble in the first place? Just don’t go crazy and then regret the 8″ lift and 42″ tires when you’re trying to park at the grocery store.
Tire Size Conversion
When you see a tire size, like “LT245/75R17”, what does that even mean?
Basically, tire size is broken up in three pieces: tire width, sidewall height, and wheel size. The first number is tire width in millimeters- the bigger the number the wider the tire. Next is the ratio of width to sidewall height- the bigger the number, the taller the sidewall (more rubber). Last is the wheel diameter; 17” is the smallest rim you can run on the F-250.
Another size format you’ll see looks like this: 35×12.50R20LT, and is based on inches instead of millimeters. It means you have a 35″ diameter tire, 172.5″ wide with a 20″ rim. The “LT”
on the end means this tire is designed for 17/2-ton to one-ton pickups, and it can handle a lot of weight.
The stock wheels and tires on the 20179 F-250 can vary depending on the trim level. They range from 245/75/R17 (31.5″ diameter) up through 275/65R20 (34.17″ diameter).
Tire Size Philosophy
Now that you can read that ridiculous number, think back to the earlier questions regarding the kind of terrain you’ll be covering. A taller tire will give you a longer footprint (more contact with the ground), it will help you roll over taller obstacles, and it will smooth out some of the bumps. The downside is that you will lose a small percentage of your available power. Some truck owners with smaller engines find they have to change the gear ratio for better torque- but this will kill gas mileage.
A wide tire will help with flotation, or your ability to stay on top of soft surfaces like sand. It basically increases the contact patch. Very useful in muddy terrain. Unfortunately, it will also decrease your gas mileage.
A narrow tire has its own advantages. It can dig down through soft, mushy terrain and grip harder surface underneath- think about snow covering a gravel road. It will also yield better gas mileage.
Have you decided yet what your driving focus will be? Are you pulling a trailer? How about hauling a lot of weight in the bed? How much mud or sand do you see?
Generally, the bigger the wheel, the better handling you get at higher speeds such as highway driving, or when hauling a lot of cargo or towing a trailer. A 20” wheel, for example, will typically have a tire with a shorter, stiffer sidewall running at a higher pressure compared to a 177” wheel. This equates to more stability when in corners, hauling heavy loads, and lane tracking. More rotating weight, however, will increase breaking distances. This is the trade off- stability for ride quality. Also, larger wheels typically mean more expensive tires.
The smaller diameter wheel yields a smoother ride. There is more distance between the rim and the road, allowing the tire to soak up more impacts. The increased tire size means there is more distance between the contact patch and the rim, allowing a much lower air pressure when driving over rough or soft terrain. In fact, you can significantly reduce the tire pressure, down to 20 pounds or even less, to allow for a much wider footprint, which will help get you out of just about any sticky situation.
Low tire pressure will also give a much smoother ride over washboards, reducing your fatigue (or your wife’s- happy wife, happy life). Just know that running low pressures will increase heat at higher speeds, and increase the chance you’ll pop a bead if you corner too quickly or hit a bad bump. So take it slow, and have a compressor or pressurized tank on hand when you hit the pavement.
The F-250 has 177”, 178” or 20” wheels stock, depending on the package. A smaller, 176″ wheel won’t fit the newer F-250. There just isn’t enough room for brakes, spindles, etc.
So what kind of world will you be rolling in? Muddy, sticky clay? Parched desert? Wet highways? There are a few different tire patterns, with options for weight and speed ratings that will work for different scenarios.
Highway tires are probably what you got if you bought your truck new. They run very quiet, are inexpensive, and generally work well in most street and highway conditions. They’re not very durable, however, and will eventually get torn up if you encounter a lot of rock or rough roads. These tires a relatively light sidewall, so they can’t handle excessive weight and will puncture much more easily.
Trail tires are stronger than highway tires. They’re designed for the terrain most drivers see in the majority of their travels. They’re good on the highway or on a gravel road. They can handle a good amount of weight and speed. Most drivers can select this type of tire as it is a good all-around tire.
All terrain tires are more aggressive. They can handle dirt, gravel, and some mud. These tires a more aggressive look, but typically don’t sacrifice highway handling. They’re fairly quiet, yet offer more grip in the rough. They look aggressive, but don’t have the problems associated with more aggressive tires. If you are looking at a lot of overland trips, this is likely your best bet.
Mud terrain tires are the most aggressive tires you can buy. These tires have large tread blocks that act as paddles in deep mud and sand. The large voids help with clearing mud from the tread. The sidewalls have typically been reinforced for abrasion and tear resistance, and they have additional tread blocks for increased traction. These tires are great for airing down- you will be less likely to pop a bead or tear a sidewall, and you will get substantially better flotation. But they are loud at highway speeds, will reduce your gas mileage, and are typically more expensive than the others discussed.
So What Have You Decided?
If you like a rugged look, but don’t care about mileage, wear, noise, or cost, you can run a good set of 37″ M/T’s on 178″ or 20″ wheels, depending on if you have to pull a trailer to your favorite campsite. You can air down in sticky terrain, and follow a jeep into more places than you would expect. You can’t go any bigger without adding a lift, however. Personally, I like to see a 2.5″ leveling kit to bring up the nose- without it the 37’s really fill up the front wheel wells. The newer diesel trucks have so much torque, re-gearing for bigger tires is pointless.
If you want an all-around set up, go with 178″ wheels and 35″ all terrain tires. This will give you the best of all worlds, but it won’t excel in any way. It will look somewhat aggressive, but won’t break the bank.
My 2019 F-250 diesel crew cab has a leveling kit, 20″ custom wheels and 35×12.50R20LT mud terrain tires. I’ve only had it for a month, so I haven’t had a chance to really try it in different conditions. I can tell you it’s noisy on the highway, but it tracks well and can handle corners better than I expected in an 8,000-pound truck. It eats up gravel roads, but can be a rough ride on washboards. It looks great- a good mix of off-road tank and highway princess- yes, I admit it.
Whatever you choose, you now have the basics in your pocket. If you have any questions, please post them below and I’ll get you an answer!